The present invention relates to a liquid applicator assembly. In particular, although not exclusively, the invention relates to a liquid applicator assembly for topically administering herbicide to weeds by the use of a hand held device with a long stem held at one end by the user, with a roller applicator at the other end. The applicator assembly is not limited to manual applicator devices. Additionally, while the applicator assembly illustrated in the drawings is intended for domestic use, the device may be adapted for commercial and agricultural use.
Weeds have long been the scorn of the home gardener and manual removal is time consuming and tedious. Chemicals applied by spraying weeds is effective and less time consuming but there are health risks associated with applying herbicides in this manner. Additionally, plants not intended to be destroyed by the herbicide can unintentionally be damaged or destroyed. The application of herbicides by spraying also results in wastage of the herbicide, particularly where the spraying is conducted to eradicate weeds growing sparsely up through cracks in concrete or roadways,
As an alternative method of applying liquid herbicides, International Patent Specification No. WO98/42187 assigned to Green Management Limited describes a roller applicator having an elongate tubular stem able to be held by the user at one end with a roller applicator provided at the other end in the shape of a large ball. The roller applicator is constructed of porous resiliently compressible foam material. The tubular stem acts as a reservoir for the liquid herbicide. The liquid herbicide is delivered in a controlled manner to the ball for surface application of the herbicide to weeds as the ball is rolled along the ground surface.
This product suffers from a number of shortcomings. Since the ball has a large surface area which is in direct contact with the ground surface, the ball delivers a large amount of herbicide to the ground/concrete/road etc irrespective of whether there are weeds present on the surface. Additionally, continual contact with the ground surface causes substantial wear on the ball.
Another shortcoming is that the shape of the ball precludes it from gaining access to tight corners. Consider for example garden beds and other densely growing garden areas.
Also, its size and shape make it difficult to accurately effect spot weeding by simply dabbing herbicide from the applicator onto plants/weeds which the user decides to eradicate. Moreover, in view of the awkward shape of the ball applicator, it is difficult for the user to be selective about the plants to which the herbicide is applied. The applicator will likely kill all in its path. The large ball is also expensive to manufacture, partly because of its awkward shape requiring it to be moulded into shape and partly because of the large amount of compressible foam material required for its construction.
Another shortcoming is the difficulty in draining the liquid contained in the tubular stem. An air valve is provided to avoid a vacuum being formed in which case the stem will not drain. However this air valve is ineffective to enable full drainage of the stem and the stem requires continual filling to maintain the flow rate. This can be resolved with the stem opened to the atmosphere but with the consequent risk of spilling the contents and losing the cap. No air valves are known to resolve this problem at a reasonable cost. Moreover, it has been found that the valve provided in the above device is not temperature stable and does not operate below about 8 degrees Celsius.
Yet another problem with the above device is caused by the glue used to connect some of its component parts. The glue gives off solvents in vapour form which attack some of the plastics in the device. Especially vulnerable is a valve which controls the flow to the applicator ball.
It is therefore an object of the present invention to address at least some of the foregoing disadvantages or at least provides the public with a usefuil choice.
In accordance with a first aspect of the present invention there is provided an applicator assembly including:
a liquid applicator which is rotatably mounted on the applicator assembly, the liquid applicator having a substantially cylindrical applicator surface for applying liquid from a source thereof;
a spacer means extending radially beyond the applicator surface in a manner effective to space the applicator surface from any flat surface with which the spacer means is engaged, wherein the liquid applicator is provided with an external edge defined between the substantially cylindrical applicator surface and an end surface of the applicator, said applicator surface and said end surfaces being exposed at least adjacent to the external edge along at least a portion of the external edge.
The invention thus defines a free edge not encumbered by either the spacer means or any other part of the applicator assembly, enabling the free edge to be used as a spot applicator. This increases the versatility of the applicator assembly whose primary function is as a roller applicator.
In a preferred form of the invention, the spacer means is provided at the end of the applicator opposite the exposed end surface. The spacer means may extend radially only a short distance (2-5 mm) beyond the applicator surface. Preferably, the spacer means is a substantially planar member. The spacer means may present a continuous peripheral surface extending radially beyond the applicator surface. Alternatively, the spacer means may be discontinuous like teeth provided on a gear wheel.
The spacer means may be in the form of a spacer wheel rotatably mounted on the applicator assembly. Moreover, a gripping surface may be provided along the peripheral edge of the spacer wheel to engage with the ground for rotation of the spacer wheel. The spacer means is preferably a wear resistant material such as a polycarbonate plastic. In a preferred form of the invention, the liquid applicator and the spacer wheel move in unison. Accordingly, the spacer wheel and the liquid applicator may be attached to each other. In a most preferred form of the invention, the spacer wheel has inwardly extending spikes to penetrate the liquid applicator to enable the spacer wheel and the liquid applicator to move as a unitary assembly.
Preferably, the liquid applicator and the spacer means have coaxial rotatory axes. For this purpose, the spacer means may include an integral bush with the liquid applicator seated on the external periphery thereof, Preferably, the internal periphery of the bush is rotatably mounted on an axle of the applicator assembly.
The liquid applicator is preferably a unitary porous foam mass. Furthermore, the applicator may be resiliently compressible. High density polyurethane foam is the preferred material.
In accordance with a second aspect of the present invention there is provided an applicator assembly including:
a liquid applicator having an applicator surface to apply liquid from a source thereof;
an elongate stem having the liquid applicator arranged at one end, the stem being of sufficient length to enable the assembly to be grounded at the end with the applicator and held in the hand of an upright user at the other end; and
a guard extending proximate the applicator surface such that with the stem arranged in an operative, substantially upright position with the guard disposed forwardly of the applicator, the guard extends beyond the applicator surface in the forward direction.
The guard preferably extends past the applicator surface when the stem is disposed at a substantially upright angle of 15xc2x0 or less to the vertical.
Thus if the applicator assembly is used in the above manner for the administration of liquid herbicide, the guard will serve to protect the upright stem of any plants in the vicinity of the applicator assembly to guard against the likelihood of herbicide being applied to the stem of the plant. On the other hand, in the case of any upright plants considered to be undesirable by the user, these may be pushed aside by the forward path of the applicator assembly. In so doing, the guard of the applicator assembly intentionally bruises the cuticle or surfaces of the leaf or stem to facilitate the introduction of the herbicide to the undesirable plant.
The liquid applicator is preferably rotatably mounted relative to the guard so that it may roll relative to the ground applying herbicide to weeds or other plants in its path. For this reason, it is preferred that the liquid applicator is in the form of a cylindrical roller. The guard may thus comprise a bar extending parallel to the axis of the roller across the front of the roller. Alternatively, the guard may be in the form of an arcuate shell conforming to the contour of the applicator. For example, where the applicator is a cylindrical roller then the guard may comprise a part cylindrical shell corresponding to the curvature of the roller.
Preferably there are two guards one extending forwardly and one extending rearwardly. This enables the direction of operation of the applicator assembly to be reversed. In a most preferred form of the invention the stem is fixed relative to the guard or guards, If there are two guards, then it is most preferred that they are symmetrically arranged about a plane of symmetry extending through the stem. Advantageously, the guards form part of a housing receiving at least part of the liquid applicator.
In accordance with a third aspect of the present invention there is provided an applicator assembly including:
a liquid applicator having an applicator surface to apply liquid from a source thereof;
an elongate stem having the liquid applicator arranged at one end, the stem being of sufficient length to enable the assembly to be grounded at the end with the applicator and held in the hand of an upright user at the other end; and
a guard extending proximate the applicator surface and over at least an upper portion of the applicator surface relative to the normal use orientation.
Preferably where the liquid applicator is a cylindrical roller with a cylindrical applicator surface, the guard is in the shape of an arcuate shell conforming to the shape of the cylindrical applicator surface. Preferably the arcuate shell extends over an angle of approximately 120 degrees.
The guard will thus provide a measure of protection to desirable plants which the user does not wish to eradicate. For example the applicator assembly can be used amongst flowers in a garden bed to eradicate weeds growing around the flowers. The weeds, if regularly checked, would normally be shorter than the flowers and thus the applicator assembly can be wiped over the weeds with the guard protecting against the applicator surface touching the underside of the flowers.
In accordance with a fourth aspect of the present invention there is provided an applicator assembly including:
elongate tubular reservoir for holding liquid, there being provided at one end of the reservoir, a liquid applicator for controlled application of liquid from the reservoir, the other end of the reservoir being provided with a funnel for ease of pour of liquid into the reservoir.
The funnel thereby enhances safety in dealing with toxic chemicals and reduces wastage.
In particular, although not exclusively, it is preferred that the elongate tubular reservoir is of sufficient length to enable the applicator assembly to be grounded at the end with the applicator, and held by an upright user at the other end.
The funnel may be integrally formed with the tubular reservoir. Alternatively, the funnel may be formed separately and affixed to the tubular reservoir.
Preferably, a screw closure is engageable with a complimentary thread in the throat of the funnel. This thread may be compatible with the standard thread provided on a bottle of pre-mixed herbicide. Moreover, the angle of taper on the funnel may also correspond to the angle of taper on the neck of the bottle of pre-mixed herbicide. The screw closure may be provided with an air valve to avoid creation of a vacuum in the elongate tubular reservoir.
The tubular reservoir is preferably transparent or at least translucent to enable the user to view its contents and in particular, to check the level of liquid remaining therein when the applicator assembly is in use. The material used in the tubular reservoir may also be antistatic and incorporate ultra-violet filters.
In accordance with a fifth aspect of the present invention there is provided a method of constructing an applicator assembly having a rotary applicator for applying liquid to a surface and an auxiliary roller to transfer liquid to the rotary applicator from a liquid reservoir, the method including:
forming the rotary applicator and the auxiliary roller from porous foam material with the auxiliary roller made from the centre of the rotary applicator;
assembling the applicator assembly with the surface of the auxiliary roller in contact with the cylindrical surface of the rotary applicator and in communication with the liquid reservoir.
Preferably the ends of the auxiliary roller are adjacent or substantially coterminus with respective ends of the rotary applicator.
Preferably the rotary applicator is cylindrical and additionally the auxiliary roller is also cylindrical. Advantageously, the auxiliary roller is cored from the rotary applicator in the centre thereof. The rotary applicator will thereby be provided with a central bore for insertion of an axle/bush assembly. The axle/bush assembly may form part of a housing with the auxiliary roller retained within the housing for engagement with the rotary applicator. Desirably, as the rotary applicator rotates in use, the auxiliary roller is driven to rotate as a consequence of it being engaged with the rotary applicator.
The rotary applicator and likewise the auxiliary roller may be formed of any porous foam material capable of absorbing liquid and applying it to a surface to be wetted by the liquid. Most preferably, the foam material is resiliently compressible ie elastomeric. One particular example is high density polyurethane foam.
In accordance with a sixth aspect of the present invention there is provided an air valve comprised of a thermoplastic rubber compound which is pliable and resilient, the valve incorporating two spaced opposed surfaces which converge towards each other to meet and lie flat against each other, a path for air extending between the two opposed surfaces, the path being operable under a slight pressure differential between one side of the valve and the other to allow for passage of air from said one side of the valve to the other in the direction in which the opposed surfaces converge.
Preferably the shore hardness of the thermoplastic rubber compound is in the range between 30 and 50 and the opposed surfaces lie flat against each other in the direction of the air path for a distance in the range of 0.2 mm to 0.5 mm. In particular, the distance is in the range of 0.3 mm to 0.35 mml. A valve so configured will resist passage of water through the valve in the opposite direction to the air flow path. Additionally, the use of a thermoplastic rubber compound will provide a thermally stable valve over of a large temperature range. The compound also has excellent elastic product memory with resistance to chemicals, solvents, herbicides formulations and ultraviolet light. A preferred thermoplastic rubber compound is Santoprene, a proprietary product of Monsanto Company. See also U.S. Pat. No. 4,104,210, the contents of which are incorporated herein by reference. The Santoprene may be injection moulded providing greater consistency and accuracy of the formed product compared to compression moulded compounds.
The two opposed surfaces may be defined by thin walls. Preferably the valve is integrally moulded and fully comprises the thermoplastic rubber compound. Ideally, the valve is injection moulded. The opposed surfaces may be defined during the moulding process including the path between the meeting portions. Alternatively, the valve may be moulded xe2x80x9cclosedxe2x80x9d with a slit made therebetween the meeting portions to define a path therebetween for passage of air.
It will be appreciated that the part of the path extending between the meeting portions need not be a visible gap. In the normal configuration of the valve, the walls may seemingly provide no gap. However, the path is sufficient for passage of air. A small pressure differential on opposite sides of the meeting portion may be all that is required to effect the passage of air.
Preferably the path is defined by an opening at one end with the opposed surfaces lying against each other at the other end of the valve. A peripheral flange may surround the opening. Externally, the valve may be further provided with a necked region adjacent the flange to sealingly locate the valve in a circular valve seat conforming to the circumference of the necked region. The thin walls which internally define the opposed surfaces may also taper towards each other on the outside of the valve towards the end opposite the opening.
In accordance with a seventh aspect of the present invention there is provided a method of making an air valve, the method including:
forming the valve from a thermoplastic rubber compound which is pliable and resilient and further, forming the valve with a path for air extending therethrough and defined in part by two spaced opposed surfaces which converge towards each other and meet to lie flat against each other, with the path for air extending between the two meeting portions of the opposed surfaces, whereby the path is operable under a slight pressure differential between one side of the valve and the other to allow for passage of air from said one side of the valve to the said other in the direction in which the opposed surfaces converge.
In accordance with a eighth aspect of the present invention there is provided a flow control tap having an external threaded portion, in which the external threaded portion at least is made of a composition comprising: in combination, a thermoplastic rubber compound in the range of 15 to 35% w/w arid polypropylene in the range 65 to 85% w/w with the exclusion of polyethylene.
The elastic product memory of the external threaded portion has been found to be excellent and moreover, if the tap is used in a product assembled from plastic components using effective glues then the part is resistant to deterioration from the solvents in the glues, in particular the solvent gases expired by such glues. The tap, including an actuator portion is preferably integrally moulded from a composition having 17.5 percent thermoplastic rubber compound and 82.5 percent polypropylene. The thermoplastic rubber compound may be Santoprene a proprietary product of Monsanto Company, (see for example U.S. Pat. No. 4,104,210) with the additional polypropylene added thereto to bring the range of polypropylene within the range specified above.
The tap is preferably embodied in an applicator assembly having a complementary internal threaded portion for engagement with the external threaded portion of the tap. The material of the tap is therefore preferably softer than the body of the applicator assembly defining the internal thread to prevent stripping of the internal thread. Thus if the body of the applicator assembly is polycarbonate, the preferred range of polypropylene in the composition of the tap is 82.5% to 85%. If the body is of a softer material such as abs plastic, the proportion of polypropylene may be lower.
In accordance with a ninth aspect of the present invention there is provided a method of making a flow control tap including an external threaded portion, the method including the step of making the external threaded portion at least, from a composition which is a combination of thermoplastic rubber compound in the range of 15 to 35% and polypropylene in the range of 65 to 85%.
This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.
The invention consists in the foregoing and also envisages constructions of which the following gives examples only.